1. Field of the Invention
This invention relates generally to improvements in pipe support and hanger systems of the kind used to support liquid lines, electrical conduits and similar duct work in buildings and industrial installations.
More particularly, this invention relates to improvements in pipe support and hanger systems which have special advantage for use in corrosive environments.
2. Description of the Prior Art
Pipe support and hanger systems of the prior art typically comprise a support means attached at its upper end to an overhead beam or other structural member and fixed at its lower end to a band or hanger which cradles a pipe, duct or conduit. In most instances, it is desirable and often necessary that the support means be of adjustable length in order to accommodate different elevations of overhead support structures and to allow for the provision of a flow gradient to a supported pipe.
The support means employed by typical prior art pipe hanger systems comprises a rod member which may be exteriorly threaded at each end as is illustrated in U.S. Pat. No. 4,524,935 to Rumble or it may comprise a similar rod exteriorly threaded over its entire length as shown by the Breeden et al patent, U.S. Pat. No. 4,795,115. As is shown by the Rumble patent, the band or hanger which attaches to the lower end of the rod member can take the form of an elongated metal band bent into a generally oval shape with the ends thereof configured to register with the thread pattern of the support rod and to be held in engagement therewith by a ferrule adapted to wedge downwardly over the ends of the band. Another type of pipe hanger comprises a single loop of wire having legs extending from a bight portion of the loop with each leg configured to engage the other leg and to attach to a support rod as is shown by the Breeden et al patent. Another form of pipe hanger is described in U.S. Pat. No. 4,166,600 to Perjes. That hanger comprises a metal strip bent over at its extremities with a buckle arranged to receive the end of a threaded rod and the bent over ends of the metal strip. The end of the threaded rod is inserted through the buckle and is secured thereto by means of a nut which compresses the strip ends between the nut and the buckle. Yet another form of pipe hanger is shown in the Katis patent, U.S. Pat. No. 2,944,778. Katis describes a pipe hanger including a metal strip having enlarged apertured ends bent so as to be in a parallel relationship with the apertures superimposed. A cylindrical flange member is threaded onto a support rod and the apertured hanger ends are fixed onto the rod against the lower flange end by means of a nut threaded onto the support rod.
In some instances, pipe support and hanger systems are placed in wet and otherwise corrosive environments, particularly in industrial and residential construction at coastal sites where the hanger system may be exposed to salt spray. Metal support rods and pipe hangers corrode rapidly in such environments requiring costly maintenance and frequent replacement. It has been proposed to provide pipe support and hanger systems fabricated entirely of plastic materials which are, by nature, corrosion resistant. One such system is described in the Albro patent, U.S. Pat. No. 3,493,206. the system shown in that patent includes a support rod or tube fabricated of a plastic material and being helically threaded over its entire length. The pipe hanger itself includes a split cradle within which a pipe is held and to which is attached an end of the threaded support rod. The end portions of the cradle are formed as a pair of semi-conical, truncated bosses having sloping exterior surfaces and axially threaded interior surfaces matching the threading of the support rod. The boss portions of the split cradle are secured to the support rod by means of a keeper member which wedges onto the sloping exterior boss surfaces thus maintaining the inner boss surfaces in mating threaded relationship with the support rod. Another pipe hanger system comprising a plastic rod and ring combination is disclosed in U.S. Pat. No. 3,273,837.
There have also been attempts to produce corrosion resistant pipe hanger systems by substituting plastic materials, typically glass fiber reinforced resins, for the metal components of the traditional pipe support and hanger systems. Such substituted materials have so far proven to be structurally inferior and far more costly than the metal systems which they replace.
It can be appreciated that a pipe support and hanger system combining the structural strength and rigidity of a metal system while providing resistance to corrosive environments would provide substantial advantage in the art.